Reciprocating compressor

ABSTRACT

A reciprocating compressor includes a cylinder ( 5 ) including a cylindrical cylinder portion ( 6 ) and a cylinder head portion ( 7 ) provided on one side of the cylinder portion, and a piston mechanism ( 8 ) reciprocably fittedly inserted on an inner peripheral side of the cylinder portion and including a piston ( 9 ) defining an inside of the cylinder portion into a compression chamber ( 10 ) and a non-compression chamber ( 11 ). A bottomed hole-shaped valve body housing portion ( 7 B) is formed at the cylinder head portion. The valve body housing portion is opened to a piston side facing the piston in an axial direction of the cylinder portion. Further, a discharge valve unit ( 18 ) and a valve holding member ( 21 ) are provided in the valve body housing portion. The discharge valve unit is inserted in the valve body housing portion. The valve holding member holds the discharge valve unit in the valve body housing portion.

TECHNICAL FIELD

The present invention relates to a reciprocating compressor preferablyusable to supply and discharge compressed air for adjusting a vehicleheight to and from an air suspension mounted on a vehicle, such as afour-wheeled automobile.

BACKGROUND ART

Generally, an air suspension mounted on a vehicle as a vehicle heightadjustment apparatus can prevent or reduce a change in a height of avehicle (a vehicle height) according to, for example, a change in aweight of a load thereon, and also appropriately adjust the vehicleheight according to, for example, a preference of a driver. In thiscase, compressed air is arranged so as to be supplied from anddischarged to an in-vehicle air compressing machine (an air compressor)to and from the air suspension.

Then, the in-vehicle air compressor causes a reciprocating compressor tobe driven by an electric motor, thereby supplying the compressed airfrom this reciprocating compressor toward the air suspension.

The reciprocating compressor includes a cylinder and a piston mechanism.The cylinder includes a cylindrical cylinder portion and a cylinder headportion integrally formed on one side of the cylinder portion. Thepiston mechanism is reciprocably fittedly inserted on an innerperipheral side of the cylinder portion, and includes a piston definingan inside of the cylinder portion into a one-side chamber and anopposite-side chamber. (For example, refer to PTL 1).

CITATION LIST Patent Literature

[PTL 1] Japanese Patent Application Public Disclosure No. 2006-266268

SUMMARY OF INVENTION Technical Problem

The reciprocating compressor discussed in PTL 1 includes a dischargeport of the compressed air provided on a top dead center side of thecylinder portion, and therefore cannot reduce a piston top clearance toprevent the piston mechanism from interfering the discharge port.Therefore, this reciprocating compressor involves a problem of failingto improve a compression performance.

An object of the present invention to provide a reciprocating compressorconfigured to be able to improve the compression performance by reducingthe piston top clearance.

Solution to Problem

According to one aspect of the present invention, a reciprocatingcompressor includes a cylinder including a cylindrical cylinder portionand a cylinder head portion provided on one side of the cylinderportion, and a piston mechanism reciprocably fittedly inserted on aninner peripheral side of the cylinder portion and including a pistondefining an inside of the cylinder portion into a one-side chamber andan opposite-side chamber. A bottomed hole-shaped valve body housingportion is formed at the cylinder head portion. The valve body housingportion is opened to a piston side facing the piston in an axialdirection of the cylinder portion. A valve body unit and a holdingmechanism are provided in the valve body housing portion. The valve bodyunit is inserted in the valve body housing portion. The holdingmechanism holds the valve body unit in the valve body housing portion,and includes a communication hole establishing communication between thevalve body housing portion and the one-side chamber.

According to a preferable embodiment of the present invention, thereciprocating compressor can reduce the piston top clearance, therebyimproving the compression performance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a vertical cross-sectional view illustrating a reciprocatingair compressor according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view illustrating a vicinity of anA portion illustrated in FIG. 1 in an enlarged manner.

FIG. 3 is a plan view illustrating a piston of a piston mechanism, afixation bolt, and an intake valve as viewed from a cylinder head side.

FIG. 4 is a perspective view illustrating a discharge valve assemblyalone in an enlarged manner.

FIG. 5 is an exploded perspective view illustrating the discharge valveassembly in an exploded state.

DESCRIPTION OF EMBODIMENTS

In the following description, a reciprocating compressor according to anembodiment of the present invention will be described in detail withreference to FIGS. 1 to 5, citing a swing-type reciprocating aircompressor as an example thereof.

In FIG. 1, a swing-type reciprocating air compressor 1 includes a crankcase 2, a crankshaft 3, a cylinder 5, a piston mechanism 8, an intakevalve 15, a discharge valve unit 18, and a valve holding member 21,which will be described below.

The crank case 2 is formed as a hollow container made from, for example,an alloy material containing aluminum. The crank case 2 includes acylindrical portion 2A, a bearing mounting portion 2B, a cylindermounting portion 2C, and a cover member 2D. The cylindrical portion 2Ais opened on a front side in a direction of an axis of a rotationalshaft 4A of an electric motor 4, which will be described below. Thebearing mounting portion 2B is provided by reducing a diameter of a rearside of the cylindrical portion 2A. The cylinder mounting potion 2C isprovided so as to be opened on a radial direction of the cylindricalportion 2A. The cover member 2D is provided so as to close the openingof the front side of the cylindrical portion 2A. An inside of the crankcase 2 is defined as a crank chamber 2E for rotatably housing thecrankshaft 3. A bearing 2F for rotatably supporting the rotational shaft4A of the electric motor 4 is mounted on an inner peripheral side of thebearing mounting portion 2B. Further, a cylinder portion 6 of thecylinder 5, which will be described below, is mounted on the cylindermounting portion 2C. Further, an intake port (not illustrated) forintroducing external air (the atmosphere) is provided to the crank case2.

The crankshaft 3 is coupled integrally rotatably to a distal end of therotational shaft 4A of the electric motor 4 supported by the bearing 2Fin the bearing mounting portion 2B. This crank shaft 3 forms a drivingdevice together with the electric motor 4. A support bolt 3A is providedon the crankshaft 3 at a position eccentric from a center of a rotationof the rotational shaft 4A. Due to this configuration, the crankshaft 3causes a circulating operation of the support bolt 3A and thus areciprocating movement of the piston mechanism 8, which will bedescribed below, by being rotationally driven by the electric motor 4.

The cylinder 5 is located on an outer peripheral side of the crank case2 and provided so as to extend radially from the cylindrical portion 2A.The cylinder 5 is cylindrically formed with use of, for example, analloy material containing aluminum. More specifically, the cylinder 5includes the cylindrical cylinder portion 6, and a cylinder head portion7 integrally formed at a distal end side, which is defined to be oneside of the cylinder portion 6.

The cylinder portion 6 is made of a cylindrical member extending in theradial direction of the cylindrical portion 2A, and is attached by beingfittedly inserted in the cylinder mounting portion 2C of the crank case2 on a proximal end side (an opposite side) thereof corresponding to thecylindrical portion 2A side. A piston 9 of the piston mechanism 8, whichwill be described below, is reciprocably fittedly inserted inside thecylinder portion 6. An inner peripheral surface 6A of the cylinderportion 6 forms a sliding contact surface which a piston ring 14 of thepiston mechanism 8 is in sliding contact with. Then, the cylinder headportion 7 is integrally provided on the distal end side of the cylinderportion 6. In the present embodiment, the cylinder 5 has been describedreferring to the example in which the cylinder portion 6 and thecylinder head portion 7 are provided integrally with each other, but thecylinder portion 6 and the cylinder head portion 7 may be formed asseparate members. However, in the case where they are provided asseparate members, a seal member should be added to prevent compressedair in the cylinder from leaking outward. Therefore, it is furtherdesirable that they are formed integrally with each other.

Now, no discharge port of the compressed air is provided on the innerperipheral surface 6A of the cylinder portion 6 on the distal end sidecorresponding to the cylinder head portion 7 side, unlike theabove-described patent literature, PTL 1. Therefore, the innerperipheral surface 6A is shaped like a smooth surface steplessthroughout an entire surface in sliding contact with the piston 9 as faras a position reaching a bottom surface 7A of the cylinder head portion7. This configuration prevents the piston ring 14 from being worn due toa step of the discharge port even when the piston 9 moves closer to thebottom surface 7A of the cylinder head portion 7. Therefore, thisconfiguration allows a top dead center position of the piston 9 to beset to a position closer to the bottom surface 7A of the cylinder headportion 7.

The cylinder head portion 7 is integrally provided at the distal endside of the cylinder portion 6 so as to close the distal end side of thecylinder portion 6. For example, the cylinder head portion 7 and thecylinder portion 6 are integrally formed by performing cuttingprocessing or the like on a single parent material (a metal block). Dueto this configuration, the cylinder 5 can prevent the air from leakingfrom between the cylinder portion 6 and the cylinder head portion 7.

The cylinder head portion 7 includes the circular bottom surface 7Alocated at a deepest portion of a compression chamber 10, which will bedescribed below, and facing the piston 9. A bottomed hole-shaped valvebody housing portion 7B is formed at a central position of this bottomsurface 7A. The valve body housing portion 7B is opened to a piston sidefacing the piston 9 in an axial direction of the cylinder portion 6.Further, a supply passage 7C is provided to the cylinder head portion 7so as to extend radially from the valve body housing portion 7B. Thissupply passage 7C is configured to allow the compressed air dischargedfrom the compression chamber 10 to flow toward an air drier 23, whichwill be described below.

The valve body housing portion 7B of the cylinder head portion 7 isconfigured to house a discharge valve assembly 17, which will bedescribed below. More specifically, the discharge valve unit 18 and thevalve holding member 21 are provided in the valve body housing portion7B. The discharge valve unit 18 is inserted in the valve body housingportion 7B. The valve holding member 21 holds the discharge valve unit18 in the valve body housing portion 7B. The valve body housing portion7B is formed by a cylindrical surface 7B1, a bottom surface portion 7B2,and a female screw portion 7B3. The cylindrical surface 7B1 extendscoaxially with the inner peripheral surface 6A of the cylinder portion6. The bottom surface portion 7B2 closes a deep portion of thiscylindrical surface 7B1. The female screw portion 7B3 is formed byreducing a diameter of the deep portion side the cylindrical portion7B1.

The piston mechanism 8 is configured to discharge the compressed air inthe compression chamber 10 toward the air drier 23 side by reciprocatingin the cylinder portion 6 of the cylinder 5. The piston mechanism 8includes the piston 9, a piston rod 12, the piston ring 14, the intakevalve 15, and a fixation bolt 16, which will be described below.

The piston 9 is reciprocably fittedly inserted on the inner peripheralside of the cylinder portion 6 of the cylinder 5. Due to thisconfiguration, the piston 9 defines the inside of the cylinder portion 6into the compression chamber 10 and a non-compression chamber 11. Thecompression chamber 10 is defined as a one-side chamber located on thecylinder head portion 7 side. The non-compression chamber 11 is definedas an opposite-side chamber located on the crank case 2 side.

The piston 9 is formed by stacking a main body portion 9A and a ringholder 9B. The main body portion 9A is made of a disk-like member havinga slightly smaller diameter dimension than an inner diameter dimensionof the cylinder portion 6. A screw hole 9C is formed at a centralposition of the piston 9. The screw hole 9C extends axially so as topenetrate through across the main body portion 9A and the ring holder9B. Further, an arc-shaped communication passage 9D (refer to FIG. 3) isprovided to the piston 9 at a radially intermediate position. Thiscommunication passage 9D establishes communication between thecompression chamber 10 and the non-compression chamber 11 by penetratingthrough the main body portion 9A and the ring holder 9B. The piston ring14 is provided on an outer peripheral side of the main body portion 9Aof the piston 9 in an externally fitted state, and the piston ring 14 isfixed to an outer peripheral side of the piston 9 by the ring holder 9B.A distal end surface (a top surface) of the ring holder 9B is configuredas a flat valve body abutment surface 9B1. The valve body abutmentsurface 9B1 is used to place the intake valve 15 thereon, which will bedescribed below.

As illustrated in FIG. 1, the piston rod 12 is provided integrally withthe main body portion 9A of the piston 9, and is configured to connectthe piston 9 to the crankshaft 3 forming the driving device. One endside of the piston rod 12 in a length direction thereof is integrallyconnected to a central position of the main body portion 9A, and anopposite end side thereof extending toward the crank case 2 side in thecylinder portion 6 is connected to the crankshaft 3. The opposite endside of the piston rod 12 is configured as a cylindrical bearing supportportion 12A, and this bearing support portion 12A is rotatably attachedto a support bolt 3A of the crankshaft 3 via a bearing 13. Due to thisconfiguration, the piston rod 12 can cause the piston 9 to reciprocatewhile swinging in the cylinder portion 6 by allowing the bearing supportportion 12A to swivel according to the rotational driving of thecrankshaft 3 by the electric motor 4.

Now, the compression chamber 10 defined in the cylinder portion 6 isformed at a position between the cylinder head portion 7 and the piston9 of the piston mechanism 8. In other words, the compression chamber 10is surrounded by the cylinder portion 6, the cylinder head portion 7,the piston 9, and the valve holding member 21, and a volume thereof isminimized when the piston 9 reaches the top dead center illustrated inFIG. 2. The volume of the compression chamber 10 in this statecorresponds to a piston stop clearance.

The piston ring 14 is provided around the piston 9, and is configured insuch a manner that an outer peripheral side thereof is in slidingcontact with the inner peripheral surface 6A of the cylinder portion 6.This piston ring 14 is configured to seal between the piston 9 and thecylinder portion 6. The piston ring 14 is formed as, for example, a sealmember L-shaped in cross section that is made from a resin materialhaving an anti-wear property and a self-lubricating property. An innerdiameter side of the piston ring 14 is fixed by being sandwiched betweenthe main body portion 9A and the ring holder 9B.

The intake valve 15 is provided on the communication passage 9D of thepiston 9, which establishes the communication between the compressionchamber 10 and the non-compression chamber 11. The intake valve 15 isconfigured to open the communication passage 9D during an intake strokeand close the communication passage 9D during a compression stroke. Asillustrated in FIG. 3, the intake valve 15 is made of an elastic(spring-like) elongated circular thin plate, and includes a mountingportion 15A, a valve portion 15B, and a pair of valve spring portions15C. The mounting portion 15A is located at the central portion of thepiston 9. The valve portion 15B is located around the mounting portion15A and closes the communication passage 9D. The pair of valve springportions 15C connects the mounting portion 15A and the valve portion 15Bto each other on an opposite side of the mounting portion 15A from thevalve portion 15B.

The intake valve 15 is in abutment with a valve body abutment surface9B1 of the ring holder 9B while the mounting portion 15A is in alignmentwith the screw hole 9C of the piston 9. In this state, the intake valve15 is fixed by the fixation bolt 16, which will be described below.

The fixation bolt 16 forms a fixation member fixing the intake valve 15to the piston 9. This fixation bolt 16 is formed as, for example, a boltequipped with a hexagonal hole that includes a screw portion 16A and ahead portion 16B having the hexagonal hole. On the fixation bolt 16,while the screw portion 16A is inserted through the mounting portion15A, this screw portion 16A is threadably engaged with the screw hole9C. Due to this configuration, the fixation bolt 16 can fix the intakevalve 15 to the main body portion 9A side together with the ring holder9B. Now, as illustrated in FIG. 2, the fixation bolt 16 as the fixationmember is provided in such a manner that the head portion 16B, which isa part of the fixation bolt 16, protrudes from the piston 9 toward thecylinder head portion 7 side when the intake valve 15 is fixed to thepiston 9. In this case, because a bolt housing portion 21E housing thehead portion 16B is formed on the valve holding member 21, which will bedescribed below, with the holding member 21 facing the head portion 16Bthat has become a protruding portion, this configuration allows thepiston 9 to move closer to the bottom surface 7A of the cylinder headportion 7, thereby reducing the piston stop clearance.

The present invention is characterized by the discharge valve assembly17 including the discharge valve unit 18 and the valve holding member21, and a configuration thereof will be described next.

As illustrated in FIGS. 4 and 5, the discharge valve assembly 17 isprovided in the valve body housing portion 7B of the cylinder headportion 7. The discharge valve assembly 17 can be mounted into the valvebody housing portion 7B from the cylinder portion 6 side. The dischargevalve assembly 17 includes the discharge valve unit 18, which will bedescribed below, and the valve holding member 21. Now, a setting of thedischarge valve assembly 17, such as an discharge performance, can beeasily changed by preparing a plurality of types having differentdimensions and settings of each of the portions (for example, a diameterdimension of a passage and a spring force) from one another, and thusselecting and mounting one of this plurality of types.

The discharge valve unit 18, which constitutes a part of the dischargevalve assembly 17, is configured to form a valve unit inserted in thevalve body housing portion 7B of the cylinder head portion 7. Then, thedischarge valve unit 18 is formed as a discharge valve by including avalve body 19 and the spring member 20.

The valve body 19 is configured to be opened when the compressed air isdischarged from the compression chamber 10 via a communication hole 21Dof the valve holding member 21. The valve body 19 includes a disk-likevalve portion 19A and a cylindrical portion 19B. The valve portion 19Ais seated onto and separated from a bottom portion 21B serving as avalve seat of the valve holding member 21. The cylindrical portion 19Bis formed to have a smaller diameter than the valve portion 19A, andextends axially from the valve portion 19A. The valve body 19 is shapedin such a manner that the cylindrical portion 19B is formed to have thesmaller diameter than the valve portion 19A, by which a stepped portion19C is formed between this valve portion 19A and the cylindrical portion19B. The valve body 19 is held by the valve holding member 21 movably inthe axial direction of the cylinder portion 6.

The spring member 20 is formed as a biasing device that biases the valvebody 19 toward the bottom portion 21B of the valve holding member 21.The spring member 20 is formed as, for example, a compression coilspring having a dimension larger than the outer dimension of thecylindrical portion 19B of the valve body 19 and smaller than an innerdiameter dimension of the cylindrical portion 21A of the valve holdingmember 21. The spring member 20 is arranged between the stepped portion19C of the valve body 19 and the bottom surface portion 7B2 of the valvebody housing portion 7B.

The valve holding member 21 is configured to form a holding mechanism,and hold the valve body 19 and the spring member 20 of the dischargevalve unit 18 in the valve body housing portion 7B. The valve holdingmember 21 is formed into a bottomed cylindrical shape by including thecylindrical portion 21A inserted in the valve body housing portion 7Band the bottom portion 21B closing the piston 9 side of the cylindricalportion 21A. An annular groove 21A1 is formed on an outer peripheralside of the cylindrical portion 21A at a position on the bottom portion21B side. An O-ring 22 is attached in this annular groove 21A1. TheO-ring 22 functions to air-tightly seal between the cylindrical portion21A and the cylindrical surface 7B1 of the valve body housing portion7B. On the other hand, a male screw portion 21A2 is formed on an openingside of the cylindrical portion 21A, which corresponds to an axiallyopposite side from the annular groove 21A1. The male screw portion 21A2is threadably engaged with the female screw portion 7B3 of the valvebody housing portion 7B.

A plurality of communication openings 21C is formed at the cylindricalportion 21A of the valve holding member 21 by radially penetratingthrough intermediate positions between the annular groove 21A1 and themale screw portion 21A2. Each of the communication openings 21C isconfigured to establish communication between the compression chamber 10and the supply passage 7C of the cylinder head portion 7 in cooperationwith the communication hole 21D, which will be described below, when thevalve body 19 is opened.

The bottom portion 21B of the valve holding member 21 forms the valveseat onto which the valve body 19 is seated when the valve is closed.Further, the communication hole 21D is provided at a center of thebottom portion 21B. The communication hole 21D forms the discharge portby axially penetrating through the bottom portion 21B. The communicationhole 21D is configured to establish communication between the valve bodyhousing portion 7B and the compression chamber 10. Now, an axialdimension of the bottom portion 21B is set in such a manner that a lowersurface thereof is located on the same plane as the bottom surface 7A ofthe cylinder head portion 7.

Further, the bottom portion 21B includes the bolt housing portion 21E asa fixation member housing portion by flaring on the compression chamber10 side of the compression hole 21D. This bolt housing portion 21E isconfigured to house the columnar head portion 162 axially protrudingwhen the fixation bolt 16 is attached to the piston 9. In this case, asillustrated in FIGS. 4 and 5, the bolt housing portion 21E is formed asa hexagonal bottomed hole. Due to this configuration, the valve holdingmember 21 can be easily threadably engaged with the valve body housingportion 7B by engaging a hexagonal fastening tool (for example, a socketwrench) with the bolt housing portion 21E. The bolt housing portion 21Eis set to a slightly larger dimension than the head portion 16B toreduce the above-described piston top clearance.

Now, one example of a procedure for assembling the discharge valveassembly 17 and a procedure for mounting the discharge valve assembly 17into the cylinder head portion 7 will be described.

When the discharge valve assembly 17 is assembled, the O-ring 22 isattached into the annular groove 21A1 of the valve holding member 21.The discharge valve assembly 17 can be assembled by inserting the valvebody 19 and the spring member 20 into the cylindrical portion 21A fromthe opening side of the valve holding member 21 in this state.

After the discharge valve assembly 17 is assembled, this discharge valveassembly 17 is mounted into the cylinder head portion 7. In this case,the discharge valve assembly 17 is introduced from the opening side ofthe cylinder portion 6, and the valve holding member 21 is inserted intothe valve body housing portion 7B of the cylinder head portion 7. Inthis state, the fastening tool engaged with the bolt housing portion 21Eof the valve holding member 21 is rotated in a tightening direction. Asa result, the male screw portion 21A2 of the cylindrical portion 21A isthreadably engaged with the female screw portion 7B3 of the valve bodyhousing portion 7B, and therefore the discharge valve assembly 17 can bemounted in the valve body housing portion 7B of the cylinder headportion 7.

As illustrated in FIG. 1, the air drier 23 is mounted on the cylinder 5.The air dryer 23 includes a dryer case 23A and a moisture absorbent 23B.The dryer case 23A is made of a sealingly closed container. The waterabsorbent 23B is realized by a desiccant such as silica gel housed inthe dryer case 23A. The dryer case 23A is formed with use of a part ofthe cylinder 5, and an inside thereof is in communication with thesupply passage 7C. Then, the air dryer 23 is configured to supply anddischarge the compressed air in a dried state (dried air) when thecompressed air is supplied from the reciprocating air compressor 1 to aplurality of air suspensions (any of them is not illustrated).

The reciprocating air compression 1 according to the present embodimentis configured in the above-described manner, and an operation thereofwill be described next.

First, when the rotational shaft 4A of the electric motor 4 isrotationally driven, the crankshaft 3 is rotated together with thisrotational shaft 4A. As a result, the piston 9 connected to thecrankshaft 3 reciprocates while swinging in the cylinder portion 6, andalternately repeats the intake stroke in which the piston 9 moves awayfrom the cylinder head portion 7 and the discharge stroke in which thepiston 9 moves toward the cylinder head portion 7. In this intakestroke, the external air is introduced into the non-compression chamber11 from the intake port of the crank case 2. In the discharge stroke,while the air in the compression chamber 10 is compressed by the piston9, the compressed air is discharged by opening the valve body 19 of thedischarge valve unit 18. This discharged compressed air is supplied toeach of the air suspensions as the sufficiently dried dried air bypassing through inside the air dryer 23.

In this manner, according to the present embodiment, the bottomedhole-shaped valve body housing portion 7B, which is opened at theposition facing the piston 9 in the axial direction of the cylinderportion 6, is formed at the cylinder head portion 7. While beingconfigured in this manner, the discharge valve unit 18, which isinserted in the valve body housing portion 7B, and the valve holdingmember 21, which holds the discharge valve unit 18 in the valve bodyhousing portion 7B and includes the communication hole 21D establishingthe communication between the valve body housing portion 7B and thecompression chamber 10, are provided in the valve body housing portion7B.

Therefore, since the discharge port of the compressed air, i.e., thecommunication hole 21D of the valve holding member 21 is provided on thebottom surface 7A side of the cylinder head portion 7, the innerperipheral surface 6A of the cylinder portion 6 can be formed as thesmooth surface stepless throughout the entire surface in sliding contactwith the piston 9 as far as the position reaching the bottom surface 7Aof the cylinder head portion 7. This configuration allows the top deadcenter position of the piston 9 to be set to a position closer to thebottom surface 7A of the cylinder head portion 7. As a result, thereciprocating air compressor 1 can reduce the piston top clearance,thereby improving the compression performance thereof.

For example, a plurality of types having, for example, different springforces of the spring member 20 and different diameter dimensions of thecommunication hole 21D from one another is prepared as the dischargevalve unit 18 and the valve holding member 21. Due to this preparation,the setting such as the discharge performance can be easily changed byselecting and mounting one of the plurality of types when mounting thedischarge valve unit 18 and the valve holding member 21 into the valvebody housing portion 7B.

The discharge valve unit 18 includes the valve body 19 and the springmember 20, which biases the valve body 19 toward the valve holdingmember 21. Due to this configuration, the discharge valve unit 18 canbias the valve body 19 toward the valve holding member 21 by the springmember 20.

Further, the valve body 19 can be used as a discharge valve opened whencompressed fluid is discharged from the compression chamber 10 via thecommunication hole 21D.

The piston mechanism 8 includes the piston 9, the piston rod 12 providedintegrally with the piston 9 and connected to the crankshaft 3, thepiston ring 14 provided around the piston 9 and disposed in slidingcontact with the cylinder portion 6, the intake valve 15 provided on thecommunication passage 9D establishing the communication between thenon-compression chamber 11 and the compression chamber 10, and thefixation bolt 16 fixing the intake valve 15 to the piston 9 andincluding the head portion 16B protruding from the piston 9 toward thecylinder head portion 7 side. While the piston mechanism 8 is configuredin this manner, the bolt housing portion 21E, which houses the headportion 16B of the fixation bolt 16, is formed on the valve holdingmember 21.

Therefore, the bolt housing portion 21E can reduce the piston topclearance while avoiding the head portion 16B of the fixation bolt 16.As a result, the reciprocating air compressor 1 can improve thecompression performance thereof.

Further, the cylinder 5 includes the cylinder portion 6 and the cylinderhead portion 7 formed integrally with each other. In addition, thedischarge valve assembly 17 is configured to be mounted by beingintroduced from inside the cylinder portion 6. Therefore, there is noportion where an air leak might occur at all between the compressionchamber 10 and the air drier 23. Due to this configuration, thecompressed air can be entirely supplied from the compression chamber 10to the air drier 23.

In the embodiment, the valve body unit has been described based on theexample in which it is applied to the discharge valve unit 18 openedwhen the compressed fluid is discharged from the compression chamber 10via the communication hole 21D. However, the present invention is notlimited thereto, and, for example, the valve body unit may be configuredin such a manner that the valve body unit is applied to an intake valveunit opened when the air is introduced from outside, and this intakevalve unit is housed in the valve body housing portion of the cylinderhead portion.

In the embodiment, the valve holding member has been described based onthe example in which the valve holding member 21 serving as the holdingmechanism is formed into the bottomed cylindrical shape by including thecylindrical portion 21A and the bottom portion 21B. However, the presentinvention is not limited thereto, and, for example, the valve holdingmember may be configured in such a manner that the valve body 19 and thespring member 20 are movably housed in the valve body housing portion 7Bof the cylinder head portion 7, and only the opening side of the valvebody housing portion 7B is closed (held) by a holding mechanism formedinto a disk-like shape.

In the embodiment, the piston has been described based on the example inwhich it is embodied by the swing-type piston mechanism 8 including thepiston 9 and the piston rod 12 integrated with each other. However, thepresent invention is not limited thereto, and the above-describedconfiguration may be applied to, for example, a reciprocating compressorconfigured in such a manner that the piston rod is rotatably connectedto the piston with use of a pin.

In the embodiment, the reciprocating compressor has been described basedon the example in which it is embodied by the reciprocating aircompression 1 mounted on the vehicle, but may be applied to areciprocating compressor other than the reciprocating air compressor 1designed to be mounted on the vehicle, such as a reciprocatingcompressor for use in a factory or a construction site.

Further, in the embodiment, the reciprocating compressor has beendescribed based on the example in which it is embodied by thereciprocating air compressor 1 of single-stage compression that includesthe single cylinder 5, the single piston 8, and the like. However, thepresent invention is not limited thereto, and, for example, thereciprocating compressor may be configured to be applied to areciprocating air compressor of two-stage compression that includes twocylinders, two pistons, and the like, or a reciprocating air compressorthat includes three or more cylinders, three or more pistons, and thelike.

Possible configurations as the reciprocating compressor according to theabove-described embodiment include the following examples.

According to a first configuration of the reciprocating compressor, thereciprocating compressor includes a cylinder including a cylindricalcylinder portion and a cylinder head portion provided on one side of thecylinder portion, and a piston mechanism reciprocably fittedly insertedon an inner peripheral side of the cylinder portion and including apiston defining an inside of the cylinder portion into a one-sidechamber and an opposite-side chamber. A bottomed hole-shaped valve bodyhousing portion is formed at the cylinder head portion. The valve bodyhousing portion is opened to a piston side facing the piston in an axialdirection of the cylinder portion. A valve body unit and a holdingmechanism are provided in the valve body housing portion. The valve bodyunit is inserted in the valve body housing portion. The holdingmechanism holds the valve body unit in the valve body housing portion,and includes a communication hole establishing communication between thevalve body housing portion and the one-side chamber.

According to a second configuration, in the first configuration, thevalve body unit includes a valve body and a biasing unit configured tobias the valve body toward the holding mechanism.

According to a third configuration, in the second configuration, thevalve body is a discharge valve opened when compressed fluid isdischarged from the one-side chamber via the communication hole.

According to a fourth configuration, in any of the first to thirdconfigurations, the piston mechanism includes the piston, a piston rodprovided integrally with the piston and connected to a driving device, apiston ring provided around the piston and disposed in sliding contactwith the cylinder portion, an intake valve provided on a communicationpassage establishing communication between the opposite-side chamber andthe one-side chamber, and a fixation member fixing the intake valve tothe piston and partially protruding from the piston toward the cylinderhead portion side. A fixation member housing portion is formed at theholding mechanism. The fixation member housing portion houses theprotruding portion of the fixation member.

According to a fifth configuration, in any of the first to fourthconfiguration, the cylinder portion and the cylinder head portion areformed integrally with each other.

The present invention is not limited to the above-described embodiments,and includes various modifications. For example, the above-describedembodiments have been described in detail to facilitate betterunderstanding of the present invention, and the present invention is notnecessarily limited to the configuration including all of the describedfeatures. Further, a part of the configuration of some embodiment can bereplaced with the configuration of another embodiment, and someembodiment can also be implemented with a configuration of anotherembodiment added to the configuration of this embodiment. Further, eachembodiment can also be implemented with another configuration added,deleted, or replaced with respect to a part of the configuration of thisembodiment.

The present application claims priority under the Paris Convention toJapanese Patent Application No. 2017-012301 filed on Jan. 26, 2017. Theentire disclosure of Japanese Patent Application No. 2017-012301 filedon Jan. 26, 2017 including the specification, the claims, the drawings,and the abstract is incorporated herein by reference in its entirety.

REFERENCE SIGN LIST

-   1 reciprocating air compressor (reciprocating compressor)-   2 crank case-   3 crankshaft (driving device)-   4 electric motor (driving device)-   5 cylinder-   6 cylinder portion-   7 cylinder head portion-   8 piston mechanism-   9 piston-   9D communication passage-   10 compression chamber (one-side chamber)-   11 non-compression chamber (opposite-side chamber)-   12 piston rod-   14 piston ring-   15 intake valve-   16 fixation bolt (fixation member)-   16B head portion (protruding portion)-   17 discharge valve assembly-   18 discharge valve unit (valve body unit)-   19 valve body-   20 spring member (biasing device)-   21 valve holding member (holding mechanism)-   21D communication hole-   21E bolt housing portion (fixation member housing portion)

1. A reciprocating compressor, the reciprocating compressor comprising:a cylinder including a cylindrical cylinder portion and a cylinder headportion provided on one side of the cylinder portion; and a pistonmechanism reciprocably fittedly inserted on an inner peripheral side ofthe cylinder portion, the piston mechanism including a piston definingan inside of the cylinder portion into a one-side chamber and anopposite-side chamber, wherein a bottomed hole-shaped valve body housingportion is formed at the cylinder head portion, the valve body housingportion being opened to a piston side facing the piston in an axialdirection of the cylinder portion, wherein the valve body housingportion houses a discharge valve assembly, a valve body unit and aholding mechanism are provided in the discharge valve assembly, and theholding mechanism holding the valve body unit in the valve body housingportion and including a communication hole establishing communicationbetween the valve body housing portion and the one-side chamber.
 2. Thereciprocating compressor according to claim 1, wherein the valve bodyunit includes a valve body and a biasing device configured to bias thevalve body toward the holding mechanism.
 3. The reciprocating compressoraccording to claim 2, wherein the valve body is a discharge valve openedwhen compressed fluid is discharged from the one-side chamber via thecommunication hole.
 4. The reciprocating compressor according to claim1, wherein the piston mechanism includes the piston, a piston rodprovided integrally with the piston and connected to a driving device, apiston ring provided around the piston and disposed in sliding contactwith the cylinder portion, an intake valve provided on a communicationpassage establishing communication between the opposite-side chamber andthe one-side chamber, and a fixation member fixing the intake valve tothe piston and partially protruding from the piston toward the cylinderhead portion side, and wherein a fixation member housing portion isformed at the holding mechanism, the fixation member housing portionhousing the protruding portion of the fixation member.
 5. Thereciprocating compressor according to claim 1, wherein the cylinderportion and the cylinder head portion are formed integrally with eachother.